docs: def shutdown(self):
          """Start the connection shutdown process, cancelling any active
          consuming and closing the channel if the connection is not active.
  
          """
          if self.is_shutting_down:
              self.logger.debug('Already shutting down')
              return
  
          self.set_state(self.STATE_SHUTTING_DOWN)
          self.logger.debug('Shutting down connection')
          if not self.is_active:
              return self.channel.close()
          self.logger.debug('Sending a Basic.Cancel to RabbitMQ')
          self.channel.basic_cancel(self.on_consumer_cancelled,
                                    self.consumer_tag)